Damped flywheel having a resilient member disposed between two coaxial masses

ABSTRACT

A damped flywheel having two coaxial masses (1, 2) which are mounted for movement with respect to one another against the action of a resilient damping device (3, 130, 230) including at least one resilient member (31 to 33; 133; 231, 232) mounted for articulation on both sides of the coaxial masses. The resilient member acts generally in a radial direction between the coaxial masses in a rest position of the flywheel to occupy a stable rest position. A second coaxial mass is mounted for rotation on the first coaxial mass through bearing members (14, 114) which are arranged at either the outer or inner peripheries of the first mass.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a damped flywheel, especially for amotor vehicle, of the kind comprising two coaxial masses which aremounted for movement of one with respect to the other against the actionof resilient damping means, which comprise at least one resilient memberoperatively interposed between the said masses.

Such a damped flywheel, usually referred to as a double damped flywheel,is described for example in the documents FR-A-2 556 800, FR-A-2 571461, FR-A-2 553 858.

2. Description of the Prior Art

As is well known, in a damped flywheel for a motor vehicle, one of themasses is carried on the crankshaft of the internal combustion engine ofthe vehicle, for rotation with it, while the other mass is carried,through an interposed friction clutch, on the input shaft of thegearbox, for rotation with the latter. The said flywheel is arranged toabsorb the vibrations which occur in the drive train going from theengine to the road wheels.

In this system having the damped flywheel, the resonant frequency occursbelow the slow running mode of the internal combustion engine, so thatat starting and stopping of the engine, the system passes through theresonant frequency.

In normal running of the vehicle, resonance effects do not exist withinthe range of operating speeds of the heat engine. However it isnecessary to provide various arrangements in order to attenuate theresonance effects at starting and stopping of the engine of the motorvehicle.

Accordingly, in the document FR-A-2 571 461, an arrangement was providedhaving a torque limiter, which permits unlimited rotation of one masswith respect to the other when passing through the resonant frequency.

This torque limiter has to be designed so as to transmit maximum torquefrom the engine, and not to allow the said maximum torque to beexceeded. As a result, it is necessary to provide a safety factor, whichis such that the calibration of the limiter is not an optimum.

In the document FR-A-2 556 800, it is arranged to short circuit theresilient device of the damped flywheel and to set up a temporaryparallel coupling, in which the two masses are coupled together forsimultaneous rotation during starting of the vehicle.

This is achieved for example by means of a starter pinion which, at theinstant when the internal combustion engine is engaged, engages at thesame time in sets of teeth which are arranged correspondingly in each ofthe masses.

That arrangement is not entirely satisfactory, especially because itmakes it necessary to modify the starter of the vehicle. In addition, aphasing problem arises between the sets of teeth of each of the masses.

In the document FR-A-2 553 848, a temporary lock of the centrifugal typeis arranged to act between the two masses during starting of thevehicle.

This solution is again not entirely satisfactory, because thecentrifugal lock is capable of jamming. In addition, it calls for alarge number of components.

Furthermore, in the above mentioned documents, the resilient memberstypically consist of helical compression springs interposedcircumferentially between the two masses.

These springs, under the action of centrifugal force, can come intofrictional contact, for example, against a skirt which is part of one ofthe masses, so that abrasion effects and wear of the spring can occur.In some cases, these springs can even themselves become jammed.

It is customary to arrange for lubrication of these springs, by mountingthe latter for example in a cavity, the greater part of which is boundedby one of the masses, and which is filled at least partly with grease.It is also possible to equip the springs with anti-wear elements such aspads or channel-shaped pieces.

In addition, the torsional stiffness of the device is constant, andwithin a given space its torque transmission capacity is limited.

It is also common to provide a hysteresis friction device between thetwo masses, with a friction ring which acts differentially in order todamp the resonance effects, but control of this is not easy to achieve.

In addition, all of these arrangements can give rise to a significantfriction effect in the slow running mode of the internal combustionengine.

An object of the present invention is to overcome these drawbacks andaccordingly to provide, in a simple and inexpensive way, a novel dampedflywheel having an increased torque capacity, which is quite insensitiveto the starting and stopping of the engine of the vehicle, while beingof reduced cost and having a resilient damping device which is providedwith at least one resilient, low friction member that requires nolubrication.

SUMMARY OF THE INVENTION

In accordance with the invention, a damped flywheel of the typedescribed above is characterised in that the resilient member of theresilient damping device is mounted by articulation on each of the saidmasses, in that the said resilient member acts generally radiallybetween the said masses in the rest position of the damped flywheel, insuch a way that the said resilient member occupies a generally radialrest position and inclined working positions, and in that the said massis mounted for rotation on the first mass by interposed bearing meanswhich are arranged at one of the inner and outer peripheries of thefirst mass.

The invention enables the damped flywheel to transmit higher torques,while having a resilient member in which parasitic friction effects arereduced due to its articulated mounting. Several resilient members arepreferably provided, these being spaced apart circumferentially atregular intervals.

It will be appreciated that the position of the bearing means enablesthe resilient member to be elongated radially, which is favourable to anincrease in the relative angular displacement between the two masses,and also to torque transmission.

Examination of the various operating situations in which the heat engineis used enables the advantages conferred by the device which is thesubject of the invention to be set forth as follows:

when the engine is in the slow running mode, with the gearbox inneutral, the low stiffness associated with the low friction of thedevice leads to optimum absorption of vibrations;

when the engine is in a driving mode, and regardless of the prevailingrunning speed and the torque transmitted, the torsional stiffnesscharacteristic that evolves enables the torque to be transmitted, whilegiving optimal damping of vibrations by virtue of a level of stiffnesswhich, although it is variable, remains sufficiently low, together withreduced friction effects;

in the starting and stopping phases of the heat engine, which arecharacterised by a very low level of transmitted torque, the stiffnesscharacteristic, which is very low and which is variable continuouslywith displacement, naturally enables the resonance effect to be verygreatly attenuated (since the resonant frequency becomes variable withdisplacement), and this is achieved in the absence of any complementaryfriction device or locking device.

The stiffness of this resilient damping device is thus variable with itsdisplacement, by virtue mainly of its articulated mounting.

In general terms, the damped flywheel in accordance with the inventionis of an inexpensive form and requires no greasing of the springs.

According to another feature, the resilient member is mounted byarticulation on the inner periphery of one of the two masses, byarticulating means which are generally arranged on the same common pitchcircle as the holes which are provided on the first mass at its innerperiphery, for passage therethrough of a fastening member, such asscrews, by which the first mass is fastened to its driving shaft, whichis the crankshaft of the engine of the vehicle in application to a motorvehicle. This also favours an increase in the length of the resilientmember. The second mass may thus be mounted for rotation on the firstmass using bearing means of reduced size, which are interposed on a hubor central sleeve at the inner periphery of the first mass. Thesebearing means are then arranged radially inwardly of access holes formedin the second mass to allow passage through them of tools for securingthe fastening members on the driving shaft associated with the firstmass.

In a modification, the resilient member may be mounted by articulationat the outer periphery of the second mass, radially inwardly of bearingmeans acting at the outer periphery of the two masses. The resilientmember is then mounted by articulation on a pivot which is fixed to thefirst mass, and which is located on generally the same pitch circle asthe access holes through which the fastening members can be passed so asto secure the first mass to its driving shaft.

In one embodiment, the resilient member may be mounted on both massesdirectly by articulation. In a modification, the resilient member may bemounted by articulation on both masses through draw pieces, which arepreferably arranged in head to toe relationship.

The articulated mounting can be obtained by means of pivot pins. Thepivot pins associated with the second mass, which constitutes thereaction plate of a clutch, may be fitted between two consecutive holeswhich are arranged for the passage therethrough of a tool for tighteningthe fastening screws that secure the first mass to the crankshaft of theengine.

In a modification, the said pivot pins of the second mass may be locatedin the said holes.

The second mass may be mounted for rotation on the first mass throughbearing means such as a rolling bearing, which is interposed eitherbetween the inner periphery of the second mass and the outer peripheryof a hub or sleeve of the first mass, or between the outer periphery ofthe second mass and a component carried by the outer periphery of thefirst mass.

In one embodiment, one of the masses has at its outer periphery anannular support element, which may optionally be of divided form, forcarrying an articulated means such as a pivot pin for the mounting ofthe resilient member by articulation. In this way, the pivot pin is wellsupported, and at the same time the resilient member is located axiallyby the said support element. For example, the support element may beformed at the outer periphery of the first mass, with the second massbeing mounted for rotation at its inner periphery on bearing means, ofreduced size, which are carried by a central sleeve fixed to the firstmass. In this way a first mass is obtained having a high inertia, whilealso having a resilient member which is long in the radial direction.

According to one feature, a window can then be provided in the firstmass for ventilating the resilient member, the said window being formedin a recess of the first mass which serves for accommodating theresilient member and for defining the support element. The resilientmember is thus ventilated and may be brought very close to the secondmass, which enables the axial size of the damped flywheel to be reduced.The number of windows and the number of resilient members does of coursedepend on the applications.

The following description illustrates the invention with reference tothe attached drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in axial cross section of a damped flywheel inaccordance with the invention;

FIG. 2 is a partial view taken in the direction of the arrow 2 in FIG.1;

FIG. 3 is a view in cross section taken on the line 3--3 in FIG. 2;

FIGS. 4 and 5 are views showing the articulating draw pieces;

FIG. 6 is a diagrammatic view of the resilient damping device whichworks between the two masses;

FIG. 7 is a diagram showing the characteristic curve of the dampedflywheel in accordance with the invention;

FIG. 8 is a partial view in axial cross section, for another embodiment;

FIG. 9 is a partial view in axial cross section showing the centre ofthe double flywheel in a further embodiment;

FIG. 10 is a partial view showing another example of a resilient member;

FIG. 11 is a view seen in the direction of the arrow 11 in FIG. 10;

FIGS. 12, 13 and 14 are views similar to FIG. 11, showing furtherembodiments by way of example;

FIG. 15 is a view seen in the direction of the arrow 15 in FIG. 14;

FIG. 16 is a view similar to FIG. 11 for yet another embodiment by wayof example;

FIGS. 17 and 18 are views similar to FIGS. 10 and 11, for still furtherembodiments by way of example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a damped flywheel for a motor vehicle comprising twocoaxial masses 1, 2 which are mounted for movement of one with respectto the other against the action of a resilient damping means 3, whichcomprises at least one resilient member 31, 32, 33 working between thetwo masses 1 and 2. The second mass 2 is mounted for rotation on thefirst mass 1, through bearing means 14 of reduced size which act at theinner periphery of the two masses 1, 2.

In this example, the first mass 1 consists generally of a plate 11,which carries at its outer periphery a starter crown 12 which isarranged to be driven by the starter of the motor vehicle.

In this example the mass 1 is driven by the internal combustion engineof the motor vehicle, being fixed on to the crankshaft 100 of the saidengine by means of studs 101, and the plate 11 has a central, axiallyoriented, sleeve 13. This sleeve 13, which in this example is integralwith the plate 11, carries a bearing 14 which is interposed radiallybetween the outer periphery of the sleeve 13 and the inner periphery ofthe mass 2. The second mass 2 is thus mounted for rotation at the innerperiphery of the first mass 1, through the bearing means 14.

In the present case, the bearing 14 consists of a ball bearing which islocated axially on the mass 2 and on the sleeve 13, by shoulders whichare formed on the said components 13, 2, together with circlips whichare engaged in grooves formed in the said components 13, 2.

The mass 2 has, from place to place, holes 27 for passage through themof a tool for tightening the studs 101 so as to fasten the first mass 1to the crankshaft 100.

These holes 27 are accordingly in axial alignment with the holes 104which are formed in the plate 11 (at the inner periphery of the latter)for accommodating the studs 101 that fasten it to the crankshaft 100.The bearing means 14 are then reduced in size, because they lie on apitch circle having a diameter smaller than that of the passages 27 andof the said holes 104 in the plate 11. This enables the size of theresilient members 31, 32, 33 to be reduced, in a manner to be describedlater herein.

The second mass 2, which in this example is a casting, constitutes thereaction plate of a friction clutch which incudes a pressure plate 21, adiaphragm 22, a cover plate 23 and a friction disc 25.

In this example the cover plate 23 is in the form of a dished platehaving a central hole through its base, and it is secured through itsradial flange, by means of screws, on to the reaction plate 2. Thediaphragm 22 is mounted for tilting movement on the cover plate by meansof spigot members, one of which can be seen in the lower part of FIG. 1.

The diaphragm 22 bears on the pressure plate 21, and urges the lattertowards the reaction plate 2 so as to grip friction liners, which arecarried by the disc 25 at its outer periphery, between the said pressureplate 21 and reaction plate 2.

The disc 25 is coupled to a central hub (not shown) which is mounted inrotation on the input shaft of the gearbox.

The pressure plate 21 is coupled in rotation to the cover plate 23,being mounted, for axial movement with respect to the latter in a mannerknown per se, by means of tangential tongues 24.

The clutch is normally engaged, and, as has been mentioned above, thefriction liners of the disc 25 are gripped between the plates 2, 21.

In order to disengage the clutch, it is necessary in the present case toexert a thrust by means of a clutch release bearing 26 on the ends ofthe fingers of the diaphragm 22, so as to cause the latter to pivot insuch a way as to remove the load which is exerted by the diaphragm 22 onthe pressure plate 21, which is then transferred towards the base of thecover plate 23 by means of the tangential tongues 24.

Thus the first mass is mounted in rotation on a driving shaft, thecrankshaft of the internal combustion engine, while the second mass 2 iscoupled in rotation to a driven shaft, which is the input shaft of thegearbox, by means of a friction clutch 2, 21 to 25.

In this example, in accordance with one feature of the invention, theresilient member 31, 32, 33 of the resilient damping device 3 is mountedby articulation on both of the said masses 1, 2. The said resilientmember works in a generally radial direction between the said masses inthe rest position of the damped flywheel, in such a way that the saidresilient member occupies a generally radial rest position and inclinedworking positions.

In the present case, the said resilient member is mounted byarticulation on the two masses 1, 2 by means of draw pieces 4, 5 whichcan be seen best in FIGS. 4 and 5. The draw pieces are of matching formsone to the other, and in the present case they are of metal.

More precisely, in FIGS. 1 to 5 three resilient members 31, 32, 33 inthe form of identical coil springs are provided with draw pieces 4, 5for increasing the torque which is transmitted.

There are four sets of draw pieces 4, 5 and springs 31, 32, 33 which arespaced apart circumferentially at regular intervals. Two of these areshown in FIG. 2.

In the present example, the springs 31, 32, 33 are adjacent to thesecond mass, and extend parallel to the latter.

To this end, in each set 4, 5, 31, 32, 33 mentioned above, the plate 11is formed with windows 16 and recesses 17. The recesses 17 are formedmainly at the outer periphery of the plate 11 of the mass 1, facingtowards the mass 2, while the windows 16 extend from the inner peripheryof the plate 11, radially outwardly of the studs 101.

The recesses 17 and the windows 16 enable the coil springs 31 to 33 tobe fitted. More precisely, the windows 16 enable the resilient members31, 32, 33 to be properly ventilated, while, with the recesses 17,reducing axial size. The resilient members 31, 32, 33 are thus able tocome close to the second mass, lying parallel to the latter.

In this example the draw pieces 4 and 5 are in the form of tridents.They are made by press forming from metal sheet.

It is of course possible to provide other arrangements, according to theapplication. The draw pieces may be formed with one tooth, two teeth,five teeth etc. In that case, one spring, two springs, five springs etc.are provided. There is preferably an odd number of teeth and springs.

In this example the draw piece 4 has a base portion 44 with a curvedback face, together with three teeth 41, 42, 43 which are joinedintegrally to the base portion 44. The draw piece 4 has a symmetricalshape, as has the draw piece 5.

The teeth 41 and 42 are of matching forms one to the other, and each hasa chamfered free end. These teeth 41 and 42 flank, symmetrically, thecentral tooth 43 which is longer, and which has a widened free end inwhich is formed a hole 46 for fitting of a pivot pin 7, which isdescribed below and which constitutes a first articulating means.Between the teeth 42 and 43, the base portion 44 is stepped so as todefine shoulders 47, 48 which are offset axially with respect to eachother.

Between the teeth 41 and 43, the profile of the base portion 44 issymmetrical with respect to its profile between the teeth 43 and 42, sothat the said base portion is stepped at that level.

The draw piece 5, which is of similar form to the draw piece 4, has abase portion 54 with a curved back face, but this back face is notchedor recessed centrally at 55, for accommodating the pivot pin 6 whichconstitutes a second articulating means to be described below. Threeteeth 51 to 53 are joined integrally to the base portion 54.

The teeth 51 and 52 are of matching forms one to the other, and have aninclined free end. The teeth 51 and 52 flank the central tooth 53symmetrically.

This central tooth is longer than the teeth 51 and 52, and has anenlarged free end portion which is formed with a hole 56 for fitting onto a pivot pin 6.

The base portion 54 of the draw piece 5 is stepped between the teeth 52,53 and between the teeth 53, 51, this being a symmetrical arrangement soas to define shoulders 57, 58 which are offset axially with respect toeach other.

It will be noted that the shoulder 48 adjacent to the central tooth 43corresponds to a recess, while in the draw piece 5, the recesscorresponds to the shoulder 57 that faces away from the central tooth53. In this way the best use is made of the space available between thetwo base portions 44, 54 of the draw pieces, with good retention of thesprings.

According to one feature, the draw pieces 4 and 5 are mounted in head totoe relationship. In this example the teeth 41, 42, 43, and 51, 52, 53are arranged to slide in contact with each other.

In order to reduce friction effects, it is arranged that a coating 8, ofa material having a low coefficient of friction such as "Teflon", isinterposed between the two draw pieces 4 and 5 so as to facilitate therelative movement between the two draw pieces 4, 5.

The draw pieces are mounted within tubular guides 34, 35, 36. Thus theouter faces of the draw pieces 4 and 5 are arranged to rub against theinner faces of the guides 34, 35, 36, which in the present case aretubular with a rectangular internal cross section, like the teeth of thedraw pieces 4 and 5.

The guides 34, 35, 36 are preferably made of a synthetic material havinga low coefficient of friction, and they are dimensioned as a function ofthe teeth of the draw pieces 4 and 5.

Each guide 34, 35, 36 has two diametrically opposed guide ribs 40, 50which project from the longitudinal edges of the guides.

As will have been understood and as is shown in the drawings, the coilsprings 31, 32, 33 are mounted respectively on the guides 36, 34, 35,being fitted over the latter, and in particular over the ribs 40, 50,with the side edges of the guides 34, 35, 36 being rounded so as tomatch the inner periphery of the said springs (FIG. 3).

It will be appreciated that, because of the shoulders 47, 48, 57, 58,interference is avoided between two consecutive coil springs 31, 32, 33.The chances of abrasion effects arising are thus minimised.

In this connection, the central spring 32 bears at one of its ends onthe shoulders 58 of the draw piece 5, and at its other end on the recessshoulders 48 of the draw piece 4, while the spring 31 is in engagementat one of its ends on the shoulders 47 of the draw piece 4, and at itsother end on the shoulders 57 of the draw piece 5. The same is true forthe spring 33.

Thus, because of the axial offsets of the shoulders 57, 58 and 47, 48,any interference between the ends of the springs 31, 32, 33 isprevented.

These springs 312, 32, 33 work between the base portions 54, 44 whichconstitute a support means for the said springs (the radial ends of thelatter).

It will be noted that the base portions 44, 54 are profiled so as tohave a curved form between the teeth, in order to increase theengagement surface of the springs 31 to 33 (FIG. 3).

Because of the guide tubes 34, 35, 36 and the associated teeth of thedraw pieces 4, 5, any deformation of the springs 31, 32 under the actionof centrifugal force is prevented, as is jamming between them.

In this example, the draw piece 5 is articulated at its inner periphery,through its central tooth 53 and its hole 56, on a pivot pin 6 (thesecond articulating means), which is carried by and fixed to the innerperiphery of the second mass 2.

The pivot pin 6, which is force-fitted into the mass 2, has a shoulderedend for retention of the free end portion 53 between the said head andthe surface of the plate 2 which faces towards the plate 11.

The shank of the pin 6 is fixed into a needle bearing 61, which ismounted in a hole formed in the plate 2 for this purpose. This hole isarranged between two consecutive access holes 27 (FIG. 2). Its size issmaller than that of the said hole 27, and it is located on the samepitch circle as the latter.

In practice, the pivot pin 6 is force-fitted into the through hole 56 inthe tooth 53, in such a way that the draw piece 5 is articulated at itsinner periphery on the mass 2. The draw piece 4 is force-fitted, throughits hole 46, on a pivot pin 7, the ends of which are mounted byarticulation, in bearing bushes 71 which are mounted, respectively, in athrough hole in the plate 11 and in a through hole in a respectiveclosure element 15, these being carried by the plate 11 at the outerperiphery of the latter.

These elements 15 increase the inertia of the mass 1 and are adjacent tothe mass 2. They are attached by screwed fastening on to the plate 11.In this example, the elements 15 are part of a common closure ring whichstiffens the first mass 1. The position of the pivot pins 7 alsocontributes to the increase in inertia.

Thus, the plate 11 has at its outer periphery cavities which aredelimited by the plate 11 and the elements 15, for fitting of the setsof components 4, 5, 31 to 36. These cavities are in circumferentialalternation with the unrecessed portions of the plate 11.

The plate 11, which is recessed at its outer periphery, defines, withthe closure member or members 15, support elements for the pivot pins 7.

In accordance with the features of the invention, the resilient dampingmeans is accordingly mounted by articulation at its outer periphery onthe plate 11 through articulating means 7, referred to as the firstarticulating means and carried by support elements 11, 15 formed at theouter periphery of the first mass 1. In other words, the first mass 1has at its outer periphery an annular support element which is dividedcircumferentially into alternate recesses 17 and unrecessed portions ofthe plate 11. The mass 1 therefore has a high inertia. The supportelement also retains the damping device 3 against axial movement.

It will be noted that the pivot pin 7 is retained against axial movementby means of a circlip 72, which is located axially by the plate 11 andthe guide tube 34.

It will be noted that the curved profile of the base portion 44 of thedraw piece 4 enables the latter to hug the profile of the inner edge ofthe window 16, which is wider at its inner periphery than at its outerperiphery (FIG. 2), so as to retain the greatest possible amount ofmaterial, and that the profile of the base portion 54 of the draw piece5 enables the pivot pin 7 to be accommodated because of the centralnotch 55 of the draw piece, which enables the length of the springs 31to 33 to be increased.

Thus, in the rest position of the damped flywheel, the springs 31 to 33extend parallel to each other, with the central spring 33 beingorientated radially in the rest position of the damped flywheel.

This rest position, which in the present case is purely radial, isstable. In this connection, and referring for example to FIG. 6, it canbe seen that once the mass 2, for example, is displaced with respect tothe mass 1, the springs 31, 32, 33 tend to exert a return action towardsthe rest position. These springs work in compression in this case.

The line of action is thus radial in the present case.

By virtue of the arrangement provided by the invention, a resilientdamping device 3 is obtained which is of variable stiffness. In thisconnection, because of the articulated mounting, the forces exerted bythe device 3 are resolved into an active tangential force and aninactive radial force, which is directed towards the axis of theassembly (FIG. 6) and which in this example is absorbed by the secondmass.

Thus, in the slow running mode of the engine, the stiffness of thedevice 3 is low, and it then increases continuously in higher operatingmodes (at higher torques) of the engine, with the angular displacementbetween the two masses 1 and 2 increasing.

The invention enables high angular displacements to be obtained betweenthe two masses (FIGS. 7), which are comparable to those which areobtained with the better devices having circumferentially actingsprings, with a high axial displacement for absorbing vibrations duringthe slow running mode of the engine.

Thus, during starting and stopping of the engine of the motor vehicle,it passes through the resonant frequency of the engine, and very gooddamping is obtained because, during this phase, the angular displacementbetween the two masses increases rapidly, as does the stiffness of theresilient damping device 3 in accordance with the invention.

Examination of the various operating situations in which the heat engineis used enables the advantages conferred by the device which is thesubject of the invention to be set forth as follows:

when the engine is in the slow running mode, with the gearbox inneutral, the low stiffness associated with the low friction of thedevice leads to optimum absorption of vibrations;

when the engine is in a driving mode, and regardless of the prevailingrunning mode and the torque transmitted, the torsional stiffnesscharacteristic that evolves enables the torque to be transmitted, whileensuring optimum damping of vibrations by virtue of a level of stiffnesswhich, although it is variable, remains sufficiently low, together withreduced friction effects;

in the starting and stopping phases of the heat engine, which arecharacterised by a very low level of transmitted torque, the stiffnesscharacteristic, which is very low and which is continuously variablewith displacement, naturally enables the resonance effect to be verygreatly attenuated (since the resonant frequency becomes variable withdisplacement), and this is achieved in the absence of any complementaryfriction device or locking device.

In this way, a high displacement damped flywheel is obtained withoutrecourse being had to any lubrication of the resilient members of theresilient damping device 3. Thus, in FIG. 7, the abscissa represents theangular displacement D, in degrees, between the two masses, while thecoordinate represents, respectively, the transmitted torque C in Nm, andthe stiffness in Nm of the resilient device in accordance with theinvention. The curve C1 is the characteristic curve of the transmittedtorque, while the curve C2 is the curve of torsional stiffness of theresilient device. It will be noted that the stiffness may be zero in theregion of the stable rest position.

It will be noted that frictional effects at the level of the springs 31,32, 33 are minimised, due to the presence of the guides 34, 35, 36, andthat the springs 31, 32, 33 are hardly deformed, due to the presence ofthese ribbed guides 34 to 36.

In addition, the draw pieces 4, 5 are able to slide easily in contactwith each other, due to the guides 34 to 36 and the low friction coating8.

It will be noted that the concave inner edge of the window 16 (FIG. 2)is in the form of an arc of a circle, so as to permit displacement ofthe resilient damping device, which pivots (inclines) during therelative angular displacement between the two masses 1 and 2. The convexouter edge of the window 16 is also in the form of an arc of a circle.This ventilating window 16 is formed in the recess 17 (FIG. 2), andslightly reduces the inertia of the first mass.

It is of course possible to reverse the structures. Thus (FIG. 8), thesecond mass 2 can be mounted for rotation at the outer periphery of thefirst mass 1 through bearing means 114, which in this example consist ofa ball bearing 114 fitted at the outer periphery of the masses 2, 1. Theresilient members in accordance with the invention can thus have asubstantial length, while the first mass 1 has a high inertia.

To this end, the said bearing comprises a member 115 of sheet metalwhich is secured, for example by screwed fastening, to the outerperiphery of the plate 11. This member 115 constitutes the outer ring ofthe bearing, the inner ring of which is defined by the outer peripheryof the mass 2. In this case, the resilient damping device 3 is mountedby articulation at its outer periphery on the mass 2, and byarticulation at its inner periphery on the mass 1, by contrast with theembodiment in FIG. 1 in which the said device is mounted by articulationat its inner periphery on the mass 2 and at its outer periphery on themass 1.

In the present embodiment, the pivot axes 60 and 70 are surrounded byarticulating sleeves 161, 171, in which the central teeth of the drawpieces 4, 5 are engaged by their through holes. It is of course possibleto provide needle bearings in place of the sleeves 161, 175.

More precisely, the pivot pin 60 is force-fitted into the plate 11 atthe inner periphery of the latter, being shouldered for retention of thesleeve 161, while the pivot pin 70 is force-fitted at the outerperiphery of the mass 2, radially outwardly of the friction disc 25. Inthis example, the pivot pins 60 are in circumferential alternation withthe through holes, for accommodating the fastening screws (not shown),which are formed in the plate 11.

The said pivot pins 60 are fitted on the same pitch circle as the saidthrough holes for accommodating the fastening screws.

The mass 2 can of course include, at its outer periphery, an annularsupport element which may be of divided form, for fitting of the pivotpins 70. Thus, one of the masses has, in every case, an annular supportelement, which may be of divided form, at its outer periphery for thefitting of the appropriate pivot pins and for good support of thelatter.

In FIG. 9, the pivot pin 600 on which the draw piece 5 is mounted may behollow and may be fixed in a through hole 127 in the mass 2, to giveaccess for a tool for tightening the fastening studs 101. The toolpasses through the pivot pin 600, which is force-fitted in the hole 127.This hole 1 27 is therefore in alignment with the hole 104 which isarranged at the inner periphery of the plate 11, to enable theappropriate stud 101 to pass through it. Thus, the pivot pins 600 arelocated on the same pitch circle as the holes 104 in the first mass 1which are arranged for accommodating the fastening members 101, which inthis example are the studs 101.

The presence of the draw piece is of course not obligatory.

Thus, in FIGS. 10 and 11, the resilient damping device 130 can consistof a metallic ring 133 having diametrically opposed radial arms, whichcarry two portions 131, 132 for articulated mounting on the pivot pins 6and 7, respectively, of FIG. 1.

The axes of the portions 131, 132 are then in radial alignment with eachother.

In FIG. 12, it can be seen that the resilient damping device 230 canconsist of a stack of curved leaf springs 231, 232, which carry at eachof their ends sleeve portions 233, 234 for mounting of the device 230 byarticulation on the axes 7 and 6, respectively, of FIG. 1.

It can be seen from FIG. 12 that the resilient damping device has twoleaf springs 231 and two leaf springs 232 which are mounted in head totoe relationship, being in contact with each other at theircircumferential ends.

The central leaf springs 231 and 232 are curved, and are in contact witheach other, with the endmost leaf springs 231 and 232 carrying thearticulating sleeve portions 233 and 234.

The leaf springs 232, 231 are of course fixed together, for example bywelding.

In FIG. 13, the resilient damping device 330 consists of a coil spring,with a hook at each of its ends for fitting on to the pivot pins 6 and7, or to any other similar element, for example projections in the formof pins projecting from the masses.

Thus, in FIGS. 10 to 13, when a force is exerted on the ends of theresilient damping devices, the central portion of these resilientdamping devices is deformed elastically in traction. The resilientmembers of the devices in FIGS. 10 to 13 are accordingly mounted, byarticulation, on the first and second masses, directly through theirouter and inner ends.

Although in the foregoing Figures of the drawings, the resilient membersof the resilient damping devices were of the metal type, in amodification (FIGS. 14 and 15), the resilient damping members 430 can ofcourse comprise blocks 431 of resilient material.

Each block 431 works between two draw pieces 432, 433 having a generallyU-shaped cross section, one of the branches of which is extended so asto carry a spherical articulating element 434, 435, for mounting byarticulation in corresponding semi-cylindrical seatings, which areformed in the masses 1 and 2 or attached on the latter.

It will be noted that the block 431 is hollow in the centre.

The block 431 works between those branches of the draw pieces 433, 432which are not extended radially, the draw pieces being mounted in headto toe relationship. The block 431 is adhesively secured on theappropriate branches of the said draw pieces 432, 433, for example byadhesive bonding or in situ vulcanisation.

In FIG. 16, the resilient damping devices 630 comprise two supports 633,634, between which a coil spring 631 works radially.

The support 633 carries a cable which is fixed by means of a ring 637within a recess 636 in one of the masses, in this example the mass 2.The support 633 is able to slide along a cable 632. In its upper part,the support 634 carries a pivot pin 635 which is in two parts, formounting on one of the masses by articulation. The cable extends throughthe lower part of the support. Thus, one of the articulations isprovided by the cable 632 and the other by the pivot pin 635, with thesupport 633 being able to slide with respect to the support 634, beingguided by the said support.

In FIGS. 17 and 18, the resilient damping device 730 comprises a support731 of rectangular form, with an upper end 732 in the form of a loop forfitting of a pivot pin which has a central bore.

A rod 735, carrying a pivot pin 736 having a central bore, passes, witha clearance, through that side of the support 731 which is opposite tothe side that includes the loop 732. The said rod passes, with aclearance, through the block 734 of resilient material, and is fixed toa support 733.

The block 734 is secured adhesively to the support 733 and to theappropriate side of the support 731.

It will be seen that the invention opens the way to many differentapplications, and that in FIGS. 14 to 18, the resilient members work incompression in such a way that in a modification there is no need tofasten the blocks of resilient material, which are for example ofelastomeric material or rubber. For this purpose it is sufficient to fitthe blocks under precompression.

In a modification, FIG. 1, the central spring 32 may be omitted due tothe symmetry of the two springs 31, 32 acting purely radially betweenthe two masses in the rest position.

In FIG. 16, the spring 631 may be replaced by a block of resilientmaterial which is hollow in the centre.

The same is true in FIGS. 14, 15 and 17, 18, in which the blocks 431,731 may be replaced by coil springs. In that case, it is necessary toprovide the draw pieces with shoulders for the purpose of centring thesprings.

In a modification, the first mass 1 may include a plate 11 in the formof a radial disc carrying at its outer periphery an axially orientedcrown on which a closure ring 15, which can optionally be of dividedform, is fixed. The crown and the closure ring are then togetherassembled to the plate 11 by means of rivets which pass axially for thispurpose through the closure ring, the crown and the plate 11.

The mass 1 then has at its outer periphery an annular cavity whichenables the resilient damping device 3 in accordance with the inventionto be accommodated, with an annular support element being defined forfitting the first articulating means (for example the pivot pins 7), andfor increasing its inertia.

In every case, the said first articulating means 7 are then wellsupported, because they extend axially between the plate 11 and theclosure ring 15, which may be divided into annular sectors, beingengaged in the closure ring 15 and the plate 11. The first articulatingmeans are then not cantilevered, and they are accordingly wellsupported. The said first means are then in no danger of tilting.

In addition, the inertia of the first mass 1 is increased because thesupport element and the first articulating means 7 are located at theouter periphery of the first mass.

Moreover, this gives rise to an increase in the length of the resilientmember of the resilient damping device in accordance with the invention.In that way, the angular displacement between the two masses 1, 2 isincreased, leading to improved absorption of the vibrations.

In a modification, the second articulating means 6 may be located on apitch circle having a diameter slightly greater than that of the pitchcircle in the plate 11 on which the fastening members (the studs 101)are located, such that, in every case, the second articulating means 6,600 are located on generally the same pitch circle as the access holes104 in the plate 11 which are provided for accommodating the studs 101.This also leads to an increase in the length of the resilient members ofthe resilient damping device in accordance with the invention. For thispurpose, the bearing means 14 are fitted either radially inwardly of theaccess holes 27 (FIG. 1), being of small size and therefore inexpensive,or at the outer periphery of the masses 1, 2 (FIG. 8).

Although in the drawings, the first and second articulating means arealigned radially in the rest position of the damped flywheel, the lineof action being radial, in a modification these articulating means maybe unaligned radially in the rest position, with one of the articulatingmeans then being slightly offset circumferentially in the rest positionof the damper with respect to the radius that passes through the otherarticulating means.

The bearing means 14 may of course consist of a coating, for example acoating based on amorphous diamond carbon and formed, for example, onthe sleeve 13 in FIG. 1, which may be attached on the plate 11, forexample by riveting.

The number of resilient members provided will depend on the application,as will their circumferential spacing. In FIGS. 1 to 7, there are foursets. It is of course possible to provide three sets, spaced apartcircumferentially at regular intervals.

The closure ring 15 may be extended inwardly, and may be provided withwindows through which the resilient members extend.

Finally, the tools associated with the screwed fastening members 101 areof a form which is adapted for the heads of the latter. These heads maybe of the cruciform recess type or of the hexagon type. All this dependson the applications.

We claim:
 1. A damped flywheel, comprising a first and a second coaxialmass (1, 2) which are mounted for movement of one with respect to theother against the action of a resilient damping device (3, 130, 230 . .. ) comprising at least one resilient member (31 to 33; 133; 231, 232 .. . ), in which the resilient member (31 to 33; 133; 231, 232 . . . )acts generally radially between the masses in the rest position of theflywheel, in such a way that the resilient member occupies a generallyradial rest position and inclined working positions, and in which thesecond mass (2) is mounted for rotation on the first mass (1) byinterposed bearing means (14, 114) which are arranged at one of theinner and outer peripheries of the first mass (1), wherein the resilientmember (31, 32, 33, 431) is mounted for articulation on the two masses(1, 2) by means of interposed draw pieces (4, 5, 432, 433).
 2. A dampedflywheel according to claim 1, wherein the draw pieces (4, 5, 432, 433)are mounted in head to toe relationship.
 3. A damped flywheel accordingto claim 2, wherein the draw pieces (4, 5) are of matching forms one tothe other, in which each one has a base portion (44, 54) and an oddnumber of teeth (41, 42, 43; 51, 52, 53) which are joined to the saidbase portion.
 4. A damped flywheel according to claim 3, wherein thedraw pieces (4, 5) have three teeth (41, 42, 43; 51, 52, 53).
 5. Adamped flywheel according to claim 4, wherein one of the teeth (43 to53) is flanked symmetrically by the other two teeth (42, 41; 52, 51),and has a free end formed with a hole (46, 56) for mounting of a pivotpin (6, 7) therein.
 6. A damped flywheel according to claim 3, whereinthe teeth of the draw pieces (4, 5) are in contact with each other, witha layer (8) having a low coefficient of friction interposed betweenthem.
 7. A damped flywheel according to claim 6, wherein the said teethof the draw pieces (4, 5) are mounted within guide tubes (34 to 36). 8.A damped flywheel according to claim 7, wherein the said guide tubes (34to 36) are of a synthetic material having a low coefficient of friction,each one having two diametrically opposed ribs (40, 50).
 9. A dampedflywheel according to claim 8, wherein, the resilient damping devicescomprises coil springs (31, 32, 33) which are fitted over said guidetubes (34 to 36).
 10. A damped flywheel according to claim 1, wherein,one of the draw pieces (45; 432, 433) is mounted for articulation on theouter periphery of the first mass (1), while the other draw member ismounted for articulation on the inner periphery of the second mass. 11.A damped flywheel according to claim 1, wherein, one of the draw piecesis mounted for articulation on the outer periphery of the second mass(2), while the other draw member is mounted for articulation on theinner periphery of the first mass (1).
 12. A damped flywheel comprising:a first and second coaxial mass (1, 2) which are mounted for movement ofone with respect to the other against the action of a resilient dampingdevice (3, 130, 230 . . . ) comprising at least one resilient member (31to 33; 133; 231, 232 . . . ), mounted for articulation on each of saidmasses, and acting generally radially between said masses in the restposition of the flywheel, in such a way that said resilient memberoccupies a generally radial rest position and inclined workingpositions, wherein the first mass (1) comprises a plate (11) and theresilient member (31 to 33; 133; 231, 232 . . . ) is mounted forarticulation on the outer periphery of the first mass (I) and forarticulation on the inner periphery of the second mass (2), wherein, theplate (11) has a window (16), for fitting of said resilient membertherein and for ventilation of the resilient member.
 13. A dampedflywheel comprising: a first and second coaxial mass (1, 2) which aremounted for movement of one with respect to the other against the actionof a resilient damping device (3, 130, 230 . . . ) comprising at leastone resilient member (31 to 33; 133; 231, 232 . . . ), wherein theresilient member (31 to 33; 133; 231, 232 . . . ) is mounted forarticulation on each of said masses by means of interposed pivot pins(6, 7; 60, 70; 600), said resilient member acting generally radiallybetween said masses in the rest position of the flywheel, in such a waythat said resilient member occupies a generally radial rest position andinclined working positions, and said mass (2) is mounted for rotation onthe first mass (1) by interposed bearing means (14, 114) which arearranged at one of the inner and outer peripheries of the first mass (1)wherein, the pivot pin (6) is mounted between two consecutive holes (27)of the second mass (2) which are arranged for the passage therethroughof a tool for screw fastening of the first mass (1) to its associateddriving shaft.
 14. A damped flywheel comprising: a first and a secondcoaxial mass (1, 2) which are mounted for movement of one with respectto the other against the action of a resilient damping device (3, 130,230 . . . ) comprising at least one resilient member (31 to 33; 133;231, 232 . . . ), mounted for articulation on each of said masses,wherein said resilient member acts generally radially between saidmasses in the rest position of the flywheel, in such a way that saidresilient member occupies a generally radial rest position and inclinedworking positions, and second mass (2) is mounted for rotation on thefirst mass (1) by interposed bearing means (14, 114) which are arrangedat one of the inner and outer peripheries of the first mass (1), whereinthe first mass (1) is adapted to be fixed to a driving shaft, while thesecond mass (2) constitutes the reaction plate of a friction clutch,wherein, said resilient member is mounted on the inner periphery of oneof the two masses (1, 2) for articulation provided by said articulatingmeans (6, 60, 600) which are arranged generally on a common pitch circlewith the holes (104) which are formed in the first mass at an innerperiphery thereof, for passage therethrough of a fastening member (101)fastening the first mass (1) to a driving shaft.
 15. A damped flywheelaccording to claim 14, characterised in that the second mass (2) ismounted for rotation on the first mass (1) by bearing means (14) ofreduced size, which are interposed operatively between the innerperiphery of the second mass (2) and the outer periphery of a centralsleeve (13) of the first mass (1) at its inner periphery, and in thatthe said bearing means (14) are disposed radially inwardly of a throughhole (27), which is comprised in the second mass (2) for passagetherethrough of tools for the fixing of fastening members by which it issecured on the driving shaft associated with the first mass.
 16. Adamped flywheel comprising: a first and a second coaxial mass (1, 2)which are mounted for movement of one with respect to the other againstthe action of a resilient damping device (3, 130, 230 . . . ) comprisingat least one resilient member (31 to 33; 133; 231, 232 . . . ), mountedfor articulation on each of said masses, and acting generally radiallybetween said masses in the rest position of the flywheel, in such a waythat said resilient member occupies a generally radial rest position andinclined working positions, and second mass (2) is mounted for rotationon the first mass (1) by interposed bearing means (14, 114) which arearranged at one of the inner and outer peripheries of the first mass(1), wherein one of the masses (1, 2) has at an outer periphery thereofa support element, which may be of divided form, for carrying anarticulation means (7) for mounting of said elastic member byarticulation.
 17. A damped flywheel according to claim 16, characterisedin that the support element is formed at the outer periphery of thefirst mass (1), the second mass (2) being mounted for rotation at aninner periphery thereof on bearing means (14) of reduced size carried bya central sleeve (13) fixed to the first mass (1).
 18. A damped flywheelaccording to claim 17, characterised in that the said support element isdefined by recesses (17) formed in a plate (11) of the first mass (I).19. A damped flywheel according to claim 18, characterised in that awindow (16) is formed in the said recess (17) for mounting of the saidresilient member therein.
 20. A damped flywheel according to claim 18characterised in that the support element is bounded by a closure member(15), and which is fixed on the plate (11) of the first mass (1) at theouter periphery of the latter.